In the past, most cars had door locks that you had to operate manually. Obviously, that’s no longer the case since nearly all modern vehicles have power door locks operated by actuators.
A door lock actuator is basically a reversible motor (or a solenoid on some vehicles) with gears that operate the door lock. The motor reverses direction so that when you press the switch to unlock the doors, the lock moves in one direction. Then when you press the switch to lock the doors, the lock moves in the opposite direction.
Typically, on older vehicles, when you press the door lock switch, power flows through a relay to the door lock actuator. On most new vehicles, however, when you press the lock switch, a signal is sent to a control module (usually the body control module). The module then supplies the power to the actuator to unlock the door.
The concept of a door lock actuator works great—until it doesn’t. When the actuator fails (or starts to fail), you’ll likely notice one or more symptoms that make your daily commute less pleasant.
Symptoms of a Faulty Door Lock Actuator
One thing to remember is that there’s an actuator at each door. That means a faulty actuator will only affect a single lock.
If none of the locks work, the problem lies elsewhere.
With that in mind, the most common symptoms of a faulty door lock actuator include:
Power Door Lock Doesn’t Work
A single bad door lock actuator can prevent one of your car’s power door locks from working. You’ll still be able to operate the lock manually, but the power function will not work.
Power Door Lock Operates Erratically
In some instances, a bad actuator may cause the door lock to behave erratically—locking or unlocking when it should not.
Strange Noises When Operating the Power Lock
A door lock actuator that’s on its way out may make a clunking, clicking, or grinding noise during operation.
Sluggish Operation From the Door Lock
In some instances, a weak door lock actuator may still be able to operate the door lock, but operation may be sluggish and/or intermittent.